Figure 2.

Osteolytic osteosarcoma. A 35-year-old female presenting with left hip pain diagnosed with aggressive lytic osteosarcoma. AP radiograph (a) demonstrates a subtle lytic lesion (arrows) in the left superior pubic ramus extending to involve the medial acetabulum. The extent of this predominantly lytic lesion with pockets of dense osteoid matrix is better appreciated on axial CT (arrows) (b). Axial T2 fat-saturated image (c) of the same lesion (arrows) depicts multiple fluid-fluid levels (arrowheads). The patient underwent left hemipelvectomy with placement of saddle prosthesis (SP) (d). A shell of heterotrophic ossification formed around the prosthesis (arrows) (e) is an expected finding, which helps stabilize the prosthesis and should not be misinterpreted as recurrence.